Measuring probe

ABSTRACT

A measuring probe includes a stylus having a contact part, an axial motion mechanism, and a rotary motion mechanism. The axial motion mechanism includes first diaphragm structures and a moving member that allows the contact part to move in an axial direction. The rotary motion mechanism includes a second diaphragm structure and a rotating member that allows the contact part to move along a plane perpendicular to the axial direction. The first diaphragm structures are disposed at a symmetric distance with respect to the second diaphragm structure, and the second diaphragm structure is disposed between the first diaphragm structures in the axial direction. The axial motion mechanism supports the rotary motion mechanism, or the rotary motion mechanism supports the axial motion mechanism.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of the U.S. applicationSer. No. 14/789,211 filed on Jul. 1, 2015, which was based upon andclaims the benefit of priorities of the Japanese Patent Application No.2015-043036 filed on Mar. 5, 2015, the contents of which areincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a measuring probe and, in particular,to a measuring probe capable of achieving a reduced length in an axialdirection and a reduced weight as well as reduced shape errors andimproved measurement accuracy.

BACKGROUND ART

A three-dimensional measuring machine, for example, has been known as ameasuring apparatus for measuring a surface shape of an object to bemeasured by contacting with the surface thereof. Japanese Patent No.4417114 (hereinafter referred to as Patent Literature 1) describes athree-dimensional measuring machine employing a measuring probe thatcomes into contact with an object to be measured to detect the surfaceshape thereof. The measuring probe illustrated in Patent Literature 1includes: a stylus having a contact part to be in contact with (asurface of) an object to be measured; an axial motion mechanismincluding a moving member that allows the contact part to move in acentral axis direction (also referred to as a Z direction or an axialdirection O) of the measuring probe; and a rotary motion mechanismincluding a rotating member that allows the contact part to move along asurface perpendicular to the Z direction by means of rotary motion. InPatent Literature 1, the axial motion mechanism and the rotary motionmechanism are connected in series and their directions in which thecontact part of the stylus can move are set to be different from eachother.

SUMMARY OF INVENTION Technical Problem

According to the measuring probe described in FIGS. 3A and 3B in PatentLiterature 1, however, a pair of diaphragm structures (springs 64 and66) that constitutes the axial motion mechanism is disposed on a sidecloser to a tip 46 than a cardanic bearing 58, which is the rotationcenter of the rotary motion mechanism in the axial direction. Thus, themeasuring probe inevitably has an increased length in the axialdirection. Also, since the pair of diaphragm structures is eccentricallylocated in a lower part of the measuring probe, a balancing member formaking the center of gravity coincident with the rotation center haslarge mass. Furthermore, a distance between the rotation center of therotary motion mechanism and the contact part disposed at the tip of thestylus (referred to as a swivel length) is long due to the presence ofthe pair of diaphragm structures, and thus there is a possibility of anincreased error in obtaining an amount of displacement of the contactpart on the basis of the movement of the rotary motion mechanism and themovement of the axial motion mechanism. In other words, it is difficultto reduce a measurement error upon measuring an object W to be measured.

The present invention has been made in order to solve theabove-described problems in the conventional technique, and an objectthereof is to provide a measuring probe capable of achieving a reducedlength in the axial direction and a reduced weight as well as reducedshape errors and improved measurement accuracy.

Solution to Problem

A first aspect of the present invention provides a measuring probeincluding: a stylus having a contact part to be in contact with anobject to be measured; an axial motion mechanism having a moving memberthat allows the contact part to move in an axial direction; and a rotarymotion mechanism having a rotating member that allows the contact partto move along a plane perpendicular to the axial direction by means ofrotary motion. The measuring probe solves the above-described problemsby configuring such that: the axial motion mechanism includes aplurality of first diaphragm structures that allow the moving member tobe displaced, and the rotary motion mechanism includes a seconddiaphragm structure that allows the rotating member to be displaced; thesecond diaphragm structure is disposed between the plurality of firstdiaphragm structures in the axial direction; the number of the firstdiaphragm structures is set to an even number; and the respective firstdiaphragm structures are disposed at a symmetric distance with respectto the second diaphragm structure.

A second aspect of the present invention provides a measuring probeincluding: a stylus having a contact part to be in contact with anobject to be measured; an axial motion mechanism having a moving memberthat allows the contact part to move in an axial direction; and a rotarymotion mechanism having a rotating member that allows the contact partto move along a plane perpendicular to the axial direction by means ofrotary motion. The measuring probe solves the above-described problemsby configuring such that: the axial motion mechanism includes aplurality of first diaphragm structures that allow the moving member tobe displaced, and the rotary motion mechanism includes a seconddiaphragm structure that allows the rotating member to be displaced; thesecond diaphragm structure is disposed between the plurality of firstdiaphragm structures in the axial direction; and when a particular typeof the style is supported by the rotating member, the center of gravityof members supported by the second diaphragm structure coincides with arotation center of the rotary motion mechanism.

A third aspect of the present invention provides the above-describedmeasuring probe, wherein the number of the first diaphragm structures isset to an even number, and the respective first diaphragm structures aredisposed at a symmetric distance with respect to the second diaphragmstructure.

A fourth aspect of the present invention provides the above-describedmeasuring probe, wherein the axial motion mechanism supports the rotarymotion mechanism.

A fifth aspect of the present invention provides the above-describedmeasuring probe, wherein the rotary motion mechanism supports the axialmotion mechanism.

A sixth aspect of the present invention provides the above-describedmeasuring probe, wherein the rotating member includes a balancing memberon a side opposite to the stylus with respect to a rotation center ofthe rotary motion mechanism, and a distance between the rotation centerand the balancing member is adjustable.

A seventh aspect of the present invention provides the above-describedmeasuring probe including: a balance weight corresponding to mass of thestylus; and a counterbalance mechanism supported by an axial elementhousing member for supporting the axial motion mechanism, thecounterbalance mechanism keeping the stylus and the balance weight inbalance.

An eighth aspect of the present invention provides the above-describedmeasuring probe including an axial element housing member that supportsthe axial motion mechanism, and wherein the axial element housing memberis provided with a displacement detector for detecting displacement ofthe moving member.

A ninth aspect of the present invention provides the above-describedmeasuring probe, wherein the displacement detector outputs a relativeposition detection signal that allows detection of a relative positionof the moving member.

A tenth aspect of the present invention provides the above-describedmeasuring probe, wherein the displacement detector outputs an absoluteposition detection signal that allows detection of an absolute positionof the moving member.

An eleventh aspect of the present invention provides the above-describedmeasuring probe, wherein the axial element housing member is providedwith an interference optical system including an interference lightsource, a reference mirror for reflecting light from the interferencelight source, and a target mirror disposed in the moving member forreflecting light from the interference light source, the interferenceoptical system capable of causing interference of reflected light fromthe reference mirror and the target mirror to generate a plurality ofinterference fringes, and the displacement detector can detect a phaseshift of the plurality of interference fringes generated in theinterference optical system.

A twelfth aspect of the present invention provides the above-describedmeasuring probe including a preceding housing member that detachablycouples and supports a housing member that supports both of the movingmember and the rotating member with an engagement part capable ofpositioning the housing member, and wherein a reference member isprovided on an end, opposite to the stylus, of any of the rotatingmember and a member supported by the rotating member, and an orientationdetector for detecting displacement of the reference membercorresponding to a rotary movement of the stylus is housed in thepreceding housing member.

A thirteenth aspect of the present invention provides theabove-described measuring probe, wherein a reference member is providedon an end, opposite to the stylus, of any of the rotating member and amember supported by the rotating member, and an orientation detector fordetecting displacement of the reference member corresponding to a rotarymovement of the stylus is housed in a housing member that supports bothof the moving member and the rotating member.

A fourteenth aspect of the present invention provides theabove-described measuring probe, wherein the reference member is areflecting mirror for reflecting light, the measuring probe includes alight source for causing light to be incident on the reflecting mirroralong an optical axis, and the orientation detector detects displacementof reflected light, reflected from the reflecting mirror, from theoptical axis.

A fifteenth aspect of the present invention provides the above-describedmeasuring probe, wherein the optical axis is provided so as to passthrough the rotation center of the rotary motion mechanism.

A sixteenth aspect of the present invention provides the above-describedmeasuring probe including a first limiting member for limiting an amountof deformation in the plurality of first diaphragm structures within arange of elastic deformation.

A seventeenth aspect of the present invention provides theabove-described measuring probe including a second limiting member forlimiting an amount of deformation in the second diaphragm structurewithin a range of elastic deformation.

An eighteenth aspect of the present invention provides theabove-described measuring probe, wherein at least part of a gap betweena first wall member, which is disposed so as to face the moving memberand to be integral with the axial element housing member for supportingthe axial motion mechanism, and the moving member, is filled with afirst viscous material.

A nineteenth aspect of the present invention provides theabove-described measuring probe, wherein at least part of a gap betweena second wall member, which is disposed to be integral with a rotaryelement housing member for supporting the rotary motion mechanism, andany of the second diaphragm structure and the rotating member, is filledwith a second viscous material.

In the present invention, it is possible to achieve a reduced length inthe axial direction and a reduced weight as well as reduced shape errorsand improved measurement accuracy. These and other novel features andadvantages of the present invention will become apparent from thefollowing detailed description of preferred embodiments.

BRIEF DESCRIPTION OF DRAWINGS

The preferred embodiments will be described with reference to thedrawings, wherein like elements have been denoted throughout the figureswith like reference numerals, and wherein:

FIG. 1 is a schematic diagram illustrating an example of a measuringsystem that employs a measuring probe according to a first embodiment ofthe present invention;

FIG. 2A is a schematic diagram illustrating a cross section of themeasuring probe according to the present embodiment, and FIG. 2B is aschematic diagram illustrating a cross section of a measuring probeaccording to a second embodiment, which is a variation of the presentembodiment;

FIG. 3 is a block diagram illustrating a configuration of the measuringprobe and peripherals thereof;

FIG. 4A is a schematic diagram illustrating an example of a firstdiaphragm structure used in an axial motion mechanism of the measuringprobe, FIG. 4B is a schematic diagram illustrating an example of asecond diaphragm structure used in a rotary motion mechanism of themeasuring probe, and FIG. 4C is a functional diagram of the seconddiaphragm structure used in the rotary motion mechanism;

FIG. 5 is a schematic diagram illustrating a cross section of ameasuring probe according to a third embodiment of the presentinvention;

FIG. 6A is a schematic diagram illustrating a cross section of ameasuring probe according to a fourth embodiment of the presentinvention taken along line (A)-(A) shifted from a central axis O in FIG.6B, and FIG. 6B is a schematic diagram illustrating a cross section of ameasuring probe according to the fourth embodiment of the presentinvention taken along the central axis O;

FIG. 7A is a schematic diagram illustrating arrangement of components inan interference optical system according to the fourth embodiment of thepresent invention, FIG. 7B shows how interfering light is incident on adisplacement detector in the interference optical system according tothe fourth embodiment of the present invention, and FIG. 7C is a chartshowing phases and frequencies of interfering light detected by thedisplacement detector in the interference optical system according tothe fourth embodiment of the present invention;

FIG. 8A is a schematic diagram illustrating a cross section of ameasuring probe according to a fifth embodiment of the presentinvention, and FIG. 8B is a schematic diagram illustrating a crosssection of a measuring probe according to a sixth embodiment of thepresent invention;

FIG. 9A is a schematic perspective view illustrating a stylus andcounterbalance mechanisms according to the fifth embodiment of thepresent invention, FIG. 9B is a schematic upper view illustrating thestylus and the counterbalance mechanisms according to the fifthembodiment of the present invention, and FIG. 9C is a schematiccross-sectional view illustrating the stylus and the counterbalancemechanisms according to the fifth embodiment of the present invention;

FIG. 10 is a schematic diagram illustrating a cross section of ameasuring probe according to a seventh embodiment of the presentinvention;

FIG. 11A is a schematic diagram illustrating a cross section of ameasuring probe according to an eighth embodiment of the presentinvention, and FIG. 11B is a schematic diagram illustrating a crosssection of a measuring probe according to a ninth embodiment of thepresent invention; and

FIG. 12 is a schematic diagram illustrating a cross section of ameasuring probe according to a tenth embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below in detailwith reference to the drawings.

The first embodiment according to the present invention will now bedescribed with reference to FIGS. 1 to 4.

The general configuration of a measuring system 100 will be describedfirst.

As shown in FIG. 1, the measuring system 100 includes: athree-dimensional measuring machine 200 that moves a measuring probe300; an operation part 110 having manually-operated joysticks 111; and amotion controller 500 that controls movements of the three-dimensionalmeasuring machine 200. The measuring system 100 further includes: a hostcomputer 600 that operates the three-dimensional measuring machine 200via the motion controller 500 and processes measured data obtained bythe three-dimensional measuring machine 200 to determine, for example,the dimension and shape of an object W to be measured; input unit 120for inputting, for example, measurement conditions; and output unit 130for outputting a result of measurement.

Components of the measuring system 100 will be described next.

As shown in FIG. 1, the three-dimensional measuring machine 200includes: the measuring probe 300; a surface plate 210; a drivemechanism 220 provided to stand on the surface plate 210, for moving themeasuring probe 300 three-dimensionally; and a drive sensor 230 thatdetects a drive amount of the drive mechanism 220.

As shown in FIG. 2A, the measuring probe 300 includes: a stylus 306; anaxial motion mechanism 310; and a rotary motion mechanism 334. Whencoming into contact with a surface S of the object W to be measured, acontact part 348 of the stylus 306 can freely change its position inthree directions along the shape of the surface S by means of the axialmotion mechanism 310 and the rotary motion mechanism 334.

The general configuration of the measuring probe 300 will be furtherdescribed with reference to FIG. 2A. Note that for the purpose ofillustration, the longitudinal direction on the plane of paper in FIG.2A is defined as a Z direction, the horizontal direction on the plane ofthe paper is defined as an X direction, and the perpendicular directionto the plane of the paper is defined as a Y direction. Thus, thedirection of a central axis O (axial direction O) of the measuring probe300 coincides with the Z direction.

As shown in FIG. 2A, the measuring probe 300 includes: the stylus 306having the contact part 348 to be in contact with the object W to bemeasured; the axial motion mechanism 310 having a moving member 312 thatallows the contact part 348 to move in the axial direction O; and therotary motion mechanism 334 having a rotating member RP that allows thecontact part 348 to move along the plane perpendicular to the axialdirection O by means of rotary motion. The axial motion mechanism 310and the rotary motion mechanism 334 are incorporated in a probe mainbody 302 and support the stylus 306. The supporting of the axial motionmechanism 310 by the rotary motion mechanism 334 in the probe main body302 leads to the direct supporting of the stylus 306 by the movingmember 312. A plurality of styluses 306 (having the contact parts 348 ofdifferent materials, at different positions, or with different mass, forexample) are prepared.

The measuring probe 300 will be described below in detail.

As shown in FIG. 2A, the probe main body 302 includes: a main bodyhousing (rotary element housing member) 308; the rotary motion mechanism334; the axial motion mechanism 310; an orientation detector 322; adisplacement detector 326; and a signal processing circuit 329 (FIG. 3).

As shown in FIG. 2A, the main body housing 308 has a cylindrical shapewith a cover and includes an opening 308A at a lower end thereof. Themain body housing 308 supports and houses the rotary motion mechanism334 radially inside thereof.

As shown in FIG. 2A, the rotary motion mechanism 334 includes: arotating member 336 (RP); and a second diaphragm structure 340 thatallows the rotating member 336 to be displaced with respect to the mainbody housing 308.

As shown in FIG. 2A, the rotating member 336 is a member supported bythe second diaphragm structure 340. Except for a supporting part 336AA,the rotating member 336 has a generally hourglass shape symmetric aboutthe second diaphragm structure 340 in the axial direction O. Therotating member 336 integrally includes: two ring portions 336A; twoconnecting portions 336B; two cylindrical portions 336C; and two joiningportions 336D. The ring portion 336A has a ring shape. Peripheralportions of first diaphragm structures 314 and 315 (described later) arefixed to the ring portions 336A. The connecting portions 336B extendtoward radially inside of the ring portions 336A so as to face the firstdiaphragm structures 314 and 315. Each of the cylindrical portions 336Chas a hollow around its axial center. The cylindrical portions 336C areprovided integrally with the connecting portions 336B. The two joiningportions 336D are coupled to each other with the second diaphragmstructure 340 interposed therebetween. More specifically, the seconddiaphragm structure 340 is disposed between the pair of first diaphragmstructures 314 and 315 in the axial direction O, and the pair of firstdiaphragm structures 314 and 315 are disposed at a symmetric distancewith respect to the second diaphragm structure 340 (note that acompletely symmetric distance is not required but design ormanufacturing errors, for example, are tolerated). Thus, the rotationcenter of the moving member 312 (described later), generated by the pairof first diaphragm structures 314 and 315, can be made coincident withthe rotation center RC of the rotary motion mechanism 334. Thesupporting part 336AA extends from a part of the ring portion 336A in anarea external to the axial direction O and supports the displacementdetector 326.

Note that the character Lh denotes a distance between the firstdiaphragm structures 314 and 315 supported by the rotating member 336 asshown in FIG. 2A. The character Lw denotes a diameter of the innerperipheral surface of the ring portions 336A to which the firstdiaphragm structures 314 and 315 are fixed. In the present embodiment,the distance Lh is set to be greater than twice the diameter Lw(Lh>2*Lw). Thus, in an amount of displacement of the moving member 312by the first diaphragm structures 314 and 315, a percentage of amovement component on a central axis of the rotating member 336 can bemade greater than that of a rotation component with respect to thecentral axis of the rotating member 336. Thus, in the presentembodiment, the unidirectional displacement accuracy of the movingmember 312 can be enhanced (high rectilinear movement accuracy can beensured) (the distance Lh is not limited thereto, but may be smallerthan or equal to twice the diameter Lw). Note that such a relationshipcan be applied to all of the embodiments.

As shown in FIG. 2A, a distance between an outer side surface of thering portion 336A and an inner side surface of the main body housing 308is determined to regulate a tilt (displacement) of the rotating member336 so that an amount of deformation in the second diaphragm structure340 falls within the range of elastic deformation. In other words, itcan be said that the probe main body 302 includes the main body housing308 and the rotating member 336 together serving as a second limitingmember for limiting an amount of deformation in the second diaphragmstructure 340 within the range of elastic deformation.

As shown in FIG. 4B, the second diaphragm structure 340 is anelastically-deformable member having a generally disk shape. An exampleof a material for the second diaphragm structure 340 is phosphor bronze(other materials may be used). The second diaphragm structure 340 isprovided with two arc-shaped cutout portions 340E out of phase with eachother by 180 degrees in the circumferential direction thereof, and twohinge portions 340C are formed therebetween. Two arc-shaped cutoutportions 340F out of phase with each other by 180 degrees in thecircumferential direction are further provided on a radially inner sideof the cutout portions 340E and two hinge portions 340D are formedtherebetween. Due to the cutout portions 340E and 340F, a peripheralportion 340A, a rim portion 340G, and a central portion 340B areprovided from the outer side toward the inner side of the seconddiaphragm structure 340 in the radial direction.

As shown in FIG. 4B, the peripheral portion 340A is positioned at theoutermost peripheral portion of the second diaphragm structure 340 andis a portion to be fixed to the main body housing 308. The rim portion340G has a strip shape in the circumferential direction due to thecutout portions 340E and 340F provided on both sides thereof in theradial direction. The rim portion 340G is disposed on the inner side ofthe peripheral portion 340A. The rim portion 340G is connected to theperipheral portion 340A via the hinge portion 340C and connected to thecentral portion 340B via the hinge portion 340D. The central portion340B is a portion for supporting the rotating member 336 and disposed onthe inner side of the rim portion 340G. The cutout portions 340E and340F are out of phase with each other by 90 degrees. Thus, the centralportion 340B is tiltable (rotatable) in two directions with the centerof the second diaphragm structure 340 (rotation center RC) used as anaxis.

FIG. 4C is a schematic diagram illustrating a function of the seconddiaphragm structure 340. Note that the character k denotes a restoringforce per unit displacement (angle) when the central portion 340B isdisplaced (rotated).

As shown in FIG. 2A, the axial motion mechanism 310 is supportedradially inside of the rotating member (axial element housing member)336. More specifically, the rotating member 336 and the axial motionmechanism 310 together constitute a linear motion module 304. As shownin FIG. 2A, the axial motion mechanism 310 includes: the moving member312; and the pair of first diaphragm structures 314 and 315 that allowsthe moving member 312 to be displaced with respect to the rotatingmember 336.

As shown in FIG. 2A, the moving member 312 integrally includes: acoupling portion 312A; a rod portion 312B; a member disposed portion312C; and a balancing member 338 from the lower part toward the upperpart thereof in the Z direction (more specifically, the rotating memberRP, which supports the moving member 312, has the balancing member 338on a side opposite to the stylus 306 with respect to the rotation centerRC of the rotary motion mechanism 334).

The balancing member 338 has mass corresponding to the mass of aparticular stylus (a particular type of a stylus) 306. Appropriatelysetting this balancing member 338 (or adjusting a distance between therotation center RC and the balancing member 338) allows the center ofgravity of the members, including the stylus 306, supported by therotating member RP to coincide with the rotation center RC. Morespecifically, when the particular stylus 306 is supported by therotating member 336 via the moving member 312, the balancing member 338causes the center of gravity of the members supported by the seconddiaphragm structure 340 to coincide with the rotation center RC of therotary motion mechanism 334. This can prevent the central axis of theparticular stylus 306 from greatly tilting from the axial direction Oeven when the measuring probe 300 is in the horizontal position, forexample. More specifically, the stylus 306 can stay at the center in ameasurement range of the orientation detector 322 (which will bedescribed later) even when the orientation of the measuring probe 300 ischanged. This allows the employment of a simpler, smaller,higher-resolution orientation detector 322. Note that the particularstylus 306 in the present embodiment refers to a stylus assumed to bemost frequently attached to the measuring probe 300 of the presentembodiment. The “members supported by the second diaphragm structure340” include the rotating member 336, the axial motion mechanism 310, areference member 316, a flange member 342, and the stylus 306. Themember disposed portion 312C is formed below the balancing member 338and a reference member 324 is disposed on a side surface of the memberdisposed portion 312C. The rod portion 312B is formed below the memberdisposed portion 312C and disposed between the pair of first diaphragmstructures 314 and 315. The rod portion 312B is housed in the rotatingmember 336. The coupling portion 312A is formed below the rod portion312B. The flange member 342 is attached to a lower end of the couplingportion 312A.

As shown in FIG. 2A, a diameter of the opening 308A of the main bodyhousing 308 is set to be smaller than an outer diameter of the flangemember 342. A distance between an upper end 342C of the flange member342 and a lower end 308AB of the opening 308A is determined to regulateupward displacement of the flange member 342 in the Z direction so thatan amount of deformation in the pair of first diaphragm structures 314and 315 falls within the range of elastic deformation. In other words,it can be said that the probe main body 302 includes the main bodyhousing 308 and the flange member 342 together serving as a firstlimiting member for limiting an amount of deformation in the pair offirst diaphragm structures 314 and 315 within the range of elasticdeformation.

As shown in FIG. 2A, the displacement detector 326 disposed on thesupporting part 336AA faces the reference member 324 disposed on themember disposed portion 312C to detect reflected light from thereference member 324. The displacement detector 326 incorporates a lightsource (not shown) for emitting light to the reference member 324.Incremental patterns having different reflectances for light from thelight source are provided at predetermined intervals in the axialdirection O on a surface of the reference member 324 closer to thedisplacement detector 326. In other words, the reference member 324 is areflective solid-state scale. The reference member 324, the displacementdetector 326, and the light source together constitute a photoelectricincremental linear encoder that outputs a two-phase sinusoidal signal.More specifically, the rotating member 336 is provided with thedisplacement detector 326 for detecting displacement of the movingmember 312. Corresponding to the displacement of the moving member 312,the displacement detector 326 outputs a periodic signal repeated inpredetermined cycles of the incremental patterns (i.e., the displacementdetector 326 is configured to output a relative position detectionsignal that allows detection of the relative position of the movingmember 312). This periodic signal is wave-shaped by the signalprocessing circuit 329. A Z-two-phase sine wave for obtainingdisplacement of the reference member 324 in the Z direction is outputtedfrom the signal processing circuit 329.

FIG. 2B is a schematic diagram illustrating the second embodiment, whichis a variation of the reference member 324 and the displacement detector326 in the first embodiment. Here, displacement of a moving member 362is detected by a differential transformer transducer. Specifically, areference member 374 provided in the moving member 362 is a cylindricalmetal member. A displacement detector 376 has a cylindrical shape and isdisposed so as to be in proximity to and face the reference member 374.The displacement detector 376 is configured by: an exciting coil thatoscillates at a high frequency (e.g., a sinusoidal voltage of 1 kHz orgreater is used); and a set of differential-coupled receiving coilsdisposed so as to interpose the exciting coil therebetween. Thereceiving coils can detect unidirectional displacement (absoluteposition) of the reference member 374 with respect to a rotating member386. More specifically, the displacement detector 376 is configured tooutput an absolute position detection signal that allows the detectionof the absolute position of the moving member 362. Since thedifferential transformer transducer is employed to detect theunidirectional displacement (absolute position) with respect to therotating member 386, the absolute position of a contact part 398 in theaxial direction O can be easily calculated. A supporting part 386AA hasa cylindrical shape and supports the displacement detector 376 radiallyinside thereof. The other elements are similar to those in the presentembodiment. Thus, basically the first two digits of their referencenumerals are simply changed from the present embodiment and thedescription thereof will be omitted.

As shown in FIG. 4A, each of the first diaphragm structures 314 and 315is an elastically-deformable member having a generally disk shape. Anexample of a material for the first diaphragm structures 314 and 315 isphosphor bronze (other materials may be used). Here, the first diaphragmstructure 314 is identical with the first diaphragm structure 315(without being limited thereto, the first diaphragm structures 314 and315 may have shapes different from each other). Thus, only the firstdiaphragm structure 314 will be described with reference to FIG. 4A.

As shown in FIG. 4A, the first diaphragm structure 314 is provided withthree cutout portions 314D out of phase with one another by 120 degreesin the circumferential direction thereof. Due to the cutout portions314D, a peripheral portion 314A, a rim portion 314B, and a centralportion 314C are provided from the outer side toward the inner side ofthe first diaphragm structure 314 in the radial direction. Theperipheral portion 314A is positioned at the outermost peripheralportion of the first diaphragm structure 314 and is a portion to befixed to the main body housing 308. The rim portion 314B has a stripshape in the circumferential direction due to the two adjacent cutoutportions 314D and is disposed on the inner side of the peripheralportion 314A. Opposite ends of the rim portion 314B are coupled to theperipheral portion 314A and the central portion 314C, respectively. Thecentral portion 314C is a portion for supporting the moving member 312and disposed on the inner side of the rim portion 314B. Displacement ofthe moving member 312 with respect to the rotating member 336 causes thecentral portion 314C of the first diaphragm structure 314 to move in avertical direction and causes the rim portion 314B to be elasticallydeformed. Note that the configuration of the first diaphragm structureis not limited to the shape described in the present embodiment (thisapplies also to the second diaphragm structure).

As shown in FIG. 2A, another light source 318 is provided on the innerside surface of the main body housing 308. Abeam splitter 320 thatdirects light outputted from the light source 318 in the Z direction issupported by a supporting member (note that the supporting member isfixed to the inner side of the main body housing 308). The lightdirected in the Z direction (light passing through an optical axis OA)is reflected by the reference member 316 (which is a reflecting mirrorfor reflecting light) provided above the balancing member 338 of themoving member 312, i.e., provided on an end, opposite to the stylus 306,of the member supported by the rotating member RP (i.e., the probe mainbody 302 is provided with the light source 318 for causing light to beincident on the reference member 316 along the optical axis OA). Thereflected light passes through the beam splitter 320 and the orientationdetector 322 disposed on an inner upper surface of the main body housing308 (i.e., the orientation detector 322 is housed in the main bodyhousing 308 which supports both of the moving member 312 and therotating member 336) detects the light reflected from the referencemember 316. Thus, displacement (tilt) of the reference member 316changes the position of the reflected light detected by the orientationdetector 322. This allows the orientation detector 322 to detect thedisplacement of the reflected light, which is reflected from thereference member 316, from the optical axis OA. Thus, the orientationdetector 322 can detect the displacement (tilt) of the reference member316 corresponding to the rotary movement of the stylus 306. The opticalaxis OA is provided so as to pass through the rotation center RC of therotary motion mechanism 334 (i.e., the central axis O coincides with theoptical axis OA).

As shown in FIG. 2A, the reference member 316 has a concave surface soas to reduce an amount of displacement from the optical axis OA in thereflected light detected by the orientation detector 322 and thusachieve the miniaturization of the orientation detector 322. An outputfrom the orientation detector 322 is also inputted to the signalprocessing circuit 329. The output from the orientation detector 322 isthen wave-shaped by the signal processing circuit 329. A displacementvoltage (XY displacement voltage) based on the displacement of thereflected light in the XY direction from the optical axis OA, which iscaused by the change in the orientation of the reference member 316, isoutputted from the signal processing circuit 329.

As shown in FIG. 2A, the diameter of the opening 308A of the main bodyhousing 308 is set to be smaller than the outer diameter of the flangemember 342. A distance between the upper end 342C of the flange member342 and the lower end 308AB of the opening 308A is determined toregulate upward displacement of the flange member 342 in the Z directionso that an amount of deformation in the pair of first diaphragmstructures 314 and 315 falls within the range of elastic deformation. Inother words, it can be said that the probe main body 302 includes themain body housing 308 and the flange member 342 together serving as afirst limiting member for limiting an amount of deformation in the pairof first diaphragm structures 314 and 315 within the range of elasticdeformation.

As shown in FIG. 2A, along a periphery on a lower end of the flangemember 342, one pair of rollers 342A is provided at each of positions atintervals of 120 degrees in the circumferential direction thereof, i.e.,totally three pairs of rollers 342A are provided at intervals of 120degrees in the circumferential direction thereof. A permanent magnet342B is provided on the central axis O. Note that the axial direction ofthe pair of rollers 342A coincides with an approximately radialdirection toward the center of the flange member 342.

As shown in FIG. 2A, the stylus 306 includes: a flange part 344; a rodpart 346; and the contact part 348.

As shown in FIG. 2A, the flange part 344 is a member corresponding tothe flange member 342. More specifically, three balls 344A are disposedat intervals of 120 degrees in the circumferential direction of theflange part 344 so as to be each in contact with the pair of rollers342A. A magnetic member 344B (which may be a permanent magnet) to beattracted to the permanent magnet 342B is disposed in the flange part344 to correspond to the permanent magnet 342B.

As shown in FIG. 2A, the three balls 344A are each in contact with thesurfaces of the corresponding pair of rollers 342A. Thus, in a statewhere the permanent magnet 342B and the magnetic member 344B are beingattracted to each other by a predetermined force, the flange member 342is seated on (in contact with) the flange part 344 at six points. Inother words, the flange member 342 and the flange part 344 can becoupled to each other while achieving high positioning accuracy. Morespecifically, the flange part 344 and the flange member 342 togetherconstitute a kinematic joint, which is a detachable coupling mechanism(it is referred to also as a kinematic coupling). Such a kinematic jointallows for a high degree of positioning reproducibility even whenattachment and detachment between the stylus 306 and the flange member342 are repeatedly performed. Note that the kinematic joint may be acombination of V-grooves and balls without being limited to thecombination of the rollers and the balls. While employing thecombination of the rollers and the balls, the order of their arrangementmay be reversed. In other words, the present invention is not limited tothe combination of the rollers and the balls as long as seating at sixpoints can be achieved. When a large force is applied to the stylus 306from a lateral direction (direction perpendicular to the axial directionO), the stylus 306 can drop off from the flange member 342 (includingnot only a case where no balls 344A are in contact with the rollers 342Abut also a case where a part of the balls 344A is not in contact withthe corresponding rollers 342A) to prevent the breakage of the probemain body 302 (therefore, the predetermined attracting force between thepermanent magnet 342B and the magnetic member 344B is set to be a forcecorresponding to the aforementioned large force; the same applieshereinafter).

As shown in FIG. 2A, a base end of the rod part 346 is attached to theflange part 344. A tip of the rod part 346 is provided with thespherical contact part 348. Note that when no displacement in the XYdirection occurs in the stylus 306, the direction of the central axis ofthe stylus 306 coincides with the Z direction (axial direction O).

A probe signal processing part 530 will next be described with referenceto FIG. 3.

As shown in FIG. 3, the probe signal processing part 530 includes: ananalog-to-digital (A/D) circuit 532; an FPGA 534; and a counter circuit536. The A/D circuit 532 performs analog-to-digital conversion of theZ-two-phase sine wave and the XY displacement voltage, which areinputted analog signals, in order to obtain respective digital signalsthereof. More specifically, as the number of bits in thisanalog-to-digital conversion increases, a higher dynamic range andhigher sensitivity to the displacement of the stylus 306 can beachieved. The FPGA 534 converts the XY displacement voltage, which is adigital signal, into a displacement signal and outputs the signal to aposition calculating part 550. The FPGA 534 also converts theZ-two-phase sine wave, which is a digital signal, into a Z-two-phasesquare wave and outputs the Z-two-phase square wave to the countercircuit 536. The counter circuit 536 measures the Z-two-phase squarewave to obtain the displacement in the Z direction and outputs theobtained result to the position calculating part 550.

In the present embodiment, the second diaphragm structure 340 isdisposed between the pair of first diaphragm structures 314 and 315 inthe axial direction O. Thus, despite that the axial motion mechanism 310and the rotary motion mechanism 334 are connected in series in the axialdirection O, the length of a suspension mechanism configured by theaxial motion mechanism 310 and the rotary motion mechanism 334 in theaxial direction O can be made shorter than the simple addition of thelengths of the axial motion mechanism 310 and the rotary motionmechanism 334 in the axial direction O. Note that the present inventionis not limited thereto. A plurality of first diaphragm structures may beprovided without constituting such a pair.

In the present embodiment, when the particular stylus 306 is supportedby the rotating member 336, the center of gravity of the memberssupported by the second diaphragm structure 340 coincides with therotation center RC of the rotary motion mechanism 334. This can preventthe central axis of the stylus 306 from tilting from the axial directionO even when the measuring probe 300 is in the horizontal position, forexample.

Furthermore, in the present embodiment, the pair of first diaphragmstructures 314 and 315 are disposed at a symmetric distance with respectto the second diaphragm structure 340 (i.e., the rotation center RCcoincides with a midpoint between the pair of first diaphragm structures314 and 315). This enables the configuration of the balanced suspensionmechanism, the prevention of unintended deformation in the suspensionmechanism (e.g., the prevention of the rotation of the axial motionmechanism 310 at a position different from the rotation center RC), andimproved accuracy of the measuring probe 300. At the same time, evenwhen the central axis of the stylus 306 is tilted with respect to theaxial direction O, for example, such a tilt has no influence on therectilinear movement accuracy of the stylus 306 (moving member 312).Thus, a change in measurement accuracy can be prevented from occurring.Note that the present invention is not limited thereto. A pair of firstdiaphragm structures may not be disposed at a symmetric distance withrespect to the second diaphragm structure. Alternatively, even-numbered(such as 4, 6, . . . excluding 2) first diaphragm structures may beprovided, and those first diaphragm structures may be disposed atsymmetric positions with respect to the second diaphragm structure.

In the present embodiment, in order to change the position of the stylus306 in the XYZ direction, the axial motion mechanism 310 performs amovement in the Z direction and the rotary motion mechanism 334 performsa movement in the XY direction in principle. Thus, the displacement ofthe stylus 306 can be separated into components of the Z direction andthe XY direction, thereby allowing displacements in the Z direction andthe XY direction to be easily detected independently of each other. Theposition calculation can be therefore simplified. Also, detectionsensitivity in the Z direction and that in the XY direction can be setindependently of each other.

In the present embodiment, the axial motion mechanism 310 is supportedby the pair of identical first diaphragm structures 314 and 315. Thus,occurrence of the displacement of the axial motion mechanism 310 in adirection other than the Z direction can be reduced, thus ensuring highmovement accuracy in the Z direction. Also, increased responsivity canbe achieved when compared with a case where an air bearing, or the like,is concurrently used for the guiding of the moving member.

In the present embodiment, the supporting of the rotating member 336(which supports the axial motion mechanism 310) by the rotary motionmechanism 334 leads to the direct supporting of the stylus 306 by themoving member 312. Thus, when compared with a case where the axialmotion mechanism supports the moving member (which supports the rotarymotion mechanism), the mass of the members supported by the movingmember 312 can be reduced, thereby facilitating the optimization of therestoring force of the pair of first diaphragm structures 314 and 315.Consequently, displacement of the stylus 306 in the axial direction O bythe axial motion mechanism 310 can be detected with high sensitivity. Atthe same time, the responsivity of the axial motion mechanism 310 can beimproved.

In the present embodiment, the rotating member 336 that supports theaxial motion mechanism 310 is provided with the displacement detector326 for detecting displacement of the moving member 312. Morespecifically, the displacement detector 326 is supported also by therotating member 336 and detects displacement of the moving member 312capable of moving in the axial direction O of the stylus 306 withoutmoving in the XY direction in principle. Thus, the displacement detector326, even if it is not an expensive detector, can detect thedisplacement of the moving member 312 with a high resolution and caneasily correct the displacement of the moving member 312. Also, a linearencoder, or the like, can be easily employed and the moving member 312(i.e., the stylus 306) can have a long stroke. Note that the presentinvention is not limited thereto. The displacement detector may beprovided in the main body housing.

In the present embodiment, the displacement detector 326 outputs arelative position detection signal (a periodic signal repeated inpredetermined cycles) that allows the detection of the relative positionof the moving member 312. Thus, constituting a photoelectric incrementallinear encoder with the displacement detector 326 allows the avoidanceof a phenomenon in which detection sensitivity varies according to aposition to which the moving member 312 is moved while ensuring anextremely long detection range (dynamic range). Also, subjecting therelative position detection signal to analog-to-digital conversion withhigh bit number allows the detection of the position in the axialdirection O with a higher resolution. Note that the present invention isnot limited thereto. The displacement detector may be configured todetect not an incremental pattern but an absolute pattern. In otherwords, the displacement detector may be configured to output an absoluteposition detection signal that allows the detection of the absoluteposition of the moving member.

In the present embodiment, the reference member 316 is provided on anend, opposite to the stylus 306, of the balancing member 338 (providedin the moving member 312) supported by the rotating member 336, and theorientation detector 322 for detecting displacement of the referencemember 316 corresponding to a rotary movement of the stylus 306 ishoused in the main body housing 308. Thus, since a distance between thereference member 316 and the orientation detector 322 can be reduced,the measuring probe 300 can be downsized and a cost reduction can betherefore achieved. At the same time, a calculation error of thedisplacement of the contact part 348, which is calculated from thedisplacement of the reference member 316, can be reduced and thus theposition of the contact part 348 can be obtained with high accuracy.Also, since no orientation detector 322 is provided in the linear motionmodule 304, the linear motion module 304 itself can be downsized and acost reduction thereof can be therefore achieved.

In the present embodiment, the light source 318 that causes light to beincident on a reflecting mirror, or the reference member 316, along theoptical axis OA is provided, and the orientation detector 322 detectsthe displacement of the reflected light, which is reflected from thereflecting mirror, from the optical axis OA. More specifically, sincethe orientation detector 322 performs detection in a contactless manner,the orientation detector 322 can detect the displacement of thereference member 316 corresponding to the displacement of the rotatingmember 336 with high sensitivity without inhibiting the rotary motion ofthe rotating member 336. Also, since the configuration for detecting thedisplacement of the reference member 316 is an optical lever andtherefore simple, a cost reduction of the measuring probe 300 can beachieved. Note that the orientation detector is not limited thereto. Acontact type orientation detector or a contactless type orientationdetector utilizing magnetism, for example, may be employed.

In the present embodiment, the optical axis OA is provided so as to passthrough the rotation center RC. Thus, a change in reflected lightgenerated by the rotary movement of the rotating member 336 (RP)contains no displacement component in the Z direction, and thedisplacement of the reference member 316 can be therefore detected withhigher sensitivity. Note that the present invention is not limitedthereto. The optical axis OA may be configured so as not to pass throughthe rotation center RC.

In the present embodiment, the probe main body 302 includes the mainbody housing 308 and the rotating member 336, which are for limiting anamount of deformation in the second diaphragm structure 340 within therange of elastic deformation. Also, the probe main body 302 includes themain body housing 308 and the flange member 342, which are for limitingan amount of deformation in the pair of first diaphragm structures 314and 315 within the range of elastic deformation. Thus, even whenexcessively large impact is applied to the stylus 306 in a directionalong which the kinematic joint cannot function, for example, plasticdeformation, breakage, or breakdown of the pair of first diaphragmstructures 314 and 315 and the second diaphragm structure 340 can beprevented from occurring. Note that the present invention is not limitedthereto. The measuring probe may not include the configuration forlimiting an amount of deformation in the pair of first diaphragmstructures and the second diaphragm structure within the range ofelastic deformation.

In other words, in the present embodiment, the measuring probe can havea reduced length in the axial direction O and a reduced weight andachieve reduced shape errors and improved measurement accuracy.

Although the present invention has been described with reference to theabove embodiment, the present invention is not limited thereto. In otherwords, modifications and design alterations can be made withoutdeparting from the scope of the present invention.

Although the supporting of the axial motion mechanism by the rotarymotion mechanism leads to the direct supporting of the stylus by themoving member in the above-described embodiments, the present inventionis not limited thereto. For example, the present invention may beconfigured as in the third embodiment shown in FIG. 5. The thirdembodiment is different from the above-described embodiments mainly insupporting relationship between a rotary motion mechanism and an axialmotion mechanism. Thus, for components excluding those different fromthe above-described embodiments, basically the first two digits of theirreference numerals are simply changed from the above-describedembodiments and the description thereof will be omitted.

In the third embodiment, the supporting of a rotary motion mechanism 434by an axial motion mechanism 410 leads to the direct supporting of astylus 406 by a rotating member RP as shown in FIG. 5. In other words, amain body housing (axial element housing member) 408 supports the axialmotion mechanism 410. Thus, a displacement detector 428 is supported onan inner side surface of the main body housing 408. The moving member412 has a cylindrical shape symmetric with respect to a second diaphragmstructure 440 in the axial direction O.

Specifically, the moving member 412 integrally includes two cylindricalportions 412C and two joining portions 412D as shown in FIG. 5. Centralportions of first diaphragm structures 414 and 415 are fixed to thevicinities of outer edges of the two cylindrical portions 412C. An innerdiameter of the two joining portions 412D is set to be greater than aninner diameter of a hollow portion 412B of the cylindrical portion 412C.The two joining portions 412D are coupled to each other with the seconddiaphragm structure 440 interposed therebetween. Therefore, also in thepresent embodiment, the pair of first diaphragm structures 414 and 415are disposed at a symmetric distance with respect to the seconddiaphragm structure 440 in the axial direction O.

As shown in FIG. 5, a scale bracket 424 is disposed on an upper end 412Aof the moving member 412. A reference member 426, which is a scale, isdisposed on the scale bracket 424. The displacement detector 428 thatdetects reflected light from the reference member 426 is disposed toface the reference member 426. More specifically, also in the presentembodiment, the reference member 426 and the displacement detector 428constitute a photoelectric incremental linear encoder (which may be aphotoelectric absolute linear encoder) that outputs a two-phasesinusoidal signal.

As shown in FIG. 5, the rotary motion mechanism 434 is supportedradially inside of the moving member 412. More specifically, the movingmember 412 and the rotary motion mechanism 434 together constitute arotary module 404. The rotating member RP is configured by an uppermember 436, a balancing member 438, and a flange member 442. An upperend of the balancing member 438 protrudes from the upper end 412A of themoving member 412 and a reference member 416 is formed thereon. In otherwords, in the present embodiment, the reference member 416 is providedon an end of the rotating member RP opposite to the stylus 406 (notethat the relationship between the reference member 416 and anorientation detector 422 is the same as that in the above embodiment).

In the present embodiment, the mass of the member supported by therotating member RP can be reduced and displacement of the stylus 406 inthe XY direction by the rotary motion mechanism 434 can be detected withhigh sensitivity when compared with a case where the rotary motionmechanism supports the axial motion mechanism.

As shown in FIG. 5, in the present embodiment, a diameter of an opening408A of the main body housing 408 is set to be smaller than an outerdiameter of the flange member 442. A distance between an upper end 442Cof the flange member 442 and a lower end 408AB of the opening 408A isdetermined to regulate upward displacement of the flange member 442 inthe Z direction so that an amount of deformation in the pair of firstdiaphragm structures 414 and 415 falls within the range of elasticdeformation. In other words, it can be said that a probe main body 402includes the main body housing 408 and the flange member 442 togetherserving as a first limiting member for limiting an amount of deformationin the pair of first diaphragm structures 414 and 415 within the rangeof elastic deformation.

Although the displacement detector 428 constitutes a photoelectricincremental linear encoder in the third embodiment, the presentinvention is not limited thereto. For example, the present invention maybe configured as in the fourth embodiment shown in FIGS. 6A and 6B. Thefourth embodiment is different from the third embodiment in aconfiguration around a displacement detector, and thus, for componentsexcluding those around the displacement detector, basically the firsttwo digits of their reference numerals are simply changed from the thirdembodiment and the description thereof will be omitted.

In the fourth embodiment, as shown in FIGS. 6A, 6B, and 7A, a probe mainbody 452 is provided with an interference optical system IF including: alight source (interference light source) 478; a reference mirror 475 forreflecting light from the light source 478; and a reference member(target mirror) 474 disposed in a moving member 462 for reflecting lightfrom the light source 478. The interference optical system IF is capableof causing the interference of the reflected light from the referencemirror 475 and the reference member 474 to generate a plurality ofinterference fringes IL. The light source 478 and the reference mirror475 are fixed to the inner side of a main body housing 458. The lightsource 478 and the reference member 474 disposed on an upper end 462A ofthe moving member 462 are aligned in the Z direction and a beam splitter477 is disposed therebetween. The beam splitter 477 is also fixed to theinner side of the main body housing 458. These elements togetherconstitute a Michelson interference optical system IF.

As shown in FIGS. 6A, 6B, and 7A, the beam splitter 477 causes lightfrom the light source 478 to split in a direction toward the referencemirror 475. The beam splitter 477 also guides reflected light, which isreflected by the reference member 474, to a displacement detector 476facing the reference mirror 475 and the beam splitter 477.Simultaneously, light reflected by the reference mirror 475 and passedthrough the beam splitter 477 is incident on the displacement detector476. Thus, the displacement detector 476 can detect phase shifts PS ofthe plurality of interference fringes IL generated by the interferenceoptical system IF as shown in FIG. 7B.

FIG. 7C shows light intensity I of the plurality of interference fringesIL detected by the displacement detector 476. Here, the phase shift PSreflects the amount of movement of the reference member 474 in the Zdirection. Thus, an amount of displacement of the moving member 462 inthe Z direction can be obtained by obtaining the phase shift PS. Here,since the plurality of interference fringes IL are constituted byinterfering light and periodic, the phase shift PS can be obtained withhigh accuracy (it can be said also in the present embodiment that thedisplacement detector 476 is configured to output a relative positiondetection signal that allows the detection of the relative position ofthe moving member 462).

Thus, in the present embodiment, the displacement of the moving member462 in the Z direction can be obtained more accurately than in the aboveembodiment. Also, a period 1/F of the light intensity I for theplurality of interference fringes IL reflects a tilt of the referencemember 474. Thus, a slight tilt of the moving member 462 in the XYdirection can be obtained by obtaining a change in the period 1/F. Inthe present embodiment, since the slight tilt of the moving member 462in the XY direction, which is associated with the displacement of themoving member 462 in the Z direction, can also be obtained from theoutput of the displacement detector 476, the displacement of a contactpart 498 in the XY direction can be obtained with higher accuracy. Notethat the interference optical system IF of the present embodiment is notthe only system capable of obtaining a tilt of the moving member 462 inthe XY direction. In principle, the displacement detectors described inthe other embodiments can also obtain such a tilt in the XY direction.Moreover, the present embodiment is based on the assumption that onlyone wavelength is employed. If two or more wavelengths are employed,however, the displacement detector can output an absolute positiondetection signal that allows the detection of the absolute position ofthe moving member.

In the present embodiment, an orientation detector 472 is disposed on aninner upper surface of the main body housing 458 on the central axis Oas shown in FIGS. 6A and 6B. Thus, the reference member 474, thereference mirror 475, the beam splitter 477, and the light source 478together constituting the interference optical system IF and an opticalpath for the displacement detector 476 are provided at positions shownin FIG. 6B, which are shifted in the X direction from the central axisO. In the present embodiment, a flange member 492 is provided withV-grooves, instead of rollers, for positioning with a stylus 456.

In the first embodiment, when the stylus 306 to be employed is changed,the moving member is allowed to change its position in the axialdirection O according to the mass of the stylus 306. However, thepresent invention is not limited thereto. For example, the presentinvention may be configured as in the fifth embodiment shown in FIG. 8A.The fifth embodiment is different from the first embodiment mainly in acoupling state between a linear motion module and a stylus. Thus, forcomponents excluding those associated with the linear motion module andthe stylus, basically the first two digits of their reference numeralsare simply changed from the first embodiment and the description thereofwill be omitted.

In the fifth embodiment, a stylus 706 includes: balance weights 731Ccorresponding to the mass of the stylus 706; and counterbalancemechanisms 731 as shown in FIG. 8A. The counterbalance mechanisms 731are supported by a rotating member (axial element housing member) 736for supporting the axial motion mechanism 710 and configured to keep thestylus 706 and the balance weights 731C in balance in the Z direction.The counterbalance mechanisms 731 are detachable together with thestylus 706 from the probe main body 702.

Specifically, the rotating member 736 includes a cylindrical supportingpart 736AB extended downwardly in the Z direction as shown in FIG. 8A.Three or more permanent magnets 736AC are provided at equal intervals inthe circumferential direction on a lower end of the supporting part736AB.

On the other hand, three or more counterbalance mechanisms 731 areprovided in a flange part 744 of the stylus 706 so as to correspond tothe positions and number of the permanent magnets 736AC as shown inFIGS. 8A and 9A to 9C. The counterbalance mechanism 731 includes: asupporting member 731A; a support shaft 731B; and a coupling shaft 731D.A magnetic member (which may be a magnet) 731AA attractable to thepermanent magnet 736AC is provided on an upper surface of the supportingmember 731A. The support shaft 731B is fixed to the supporting member731A and the balance weight 731C is eccentrically coupled to the supportshaft 731B. The balance weight 731C is provided with the coupling shaft731D in the direction perpendicular to the Z direction, and a tip of thecoupling shaft 731D is coupled to the flange part 744.

Thus, in the present embodiment, when the stylus 706 is replaced for asingle probe main body 702, the balance weights 731C corresponding tothe mass of the changed stylus 706 are necessarily used. This allows therotating member 736 to directly receive an increase or decrease in themass of the stylus 706. More specifically, fluctuations in the initialposition of a moving member 712 in the Z direction due to differentstyluses 706 can be prevented by this configuration. In the presentembodiment, a range of motion for the moving member 712 can be reducedwhen compared with the above embodiment, thus allowing furtherminiaturization of a linear motion module 704. At the same time, thedetection range (dynamic range) can also be reduced, thus allowing thedetection of an amount of displacement of the moving member 712 with ahigher resolution.

FIG. 8B shows the sixth embodiment, which is a variation of the fifthembodiment. The sixth embodiment is different from the fifth embodimentmainly in the addition of a balancing member. Thus, basically the firsttwo digits of their reference numerals are simply changed from the fifthembodiment and description regarding configuration excluding thoseassociated with the balancing member will be basically omitted. Notethat a displacement detector is supported in the same way as the aboveembodiment.

In the sixth embodiment, a rotating member 786 includes anannular-shaped balancing member 788 on a side opposite to a stylus 756with respect to the rotation center RC of a rotary motion mechanism 784as shown in FIG. 8B. The balancing member 788 is supported by asupporting part 787 provided on an upper end of the rotating member 786.The balancing member 788 can move in engagement with the supporting part787. The supporting part 787 allows the adjustment of a distance betweenthe rotation center RC and the balancing member 788. Thus, by changingthe distance between the balancing member 788 and the rotation centerRC, the center of gravity of the rotating members 786 (member supportedby a second diaphragm structure 790) to which different styluses 756 arecoupled can be made coincident with the rotation center RC. Thus, in thepresent embodiment, higher sensitivity of a measuring probe 750 can beachieved than in the above embodiment. Note that such a balancing membercapable of adjusting its position may be applied to the structure, asshown in the fifth embodiment, in which the axial motion mechanismsupports the rotary motion mechanism.

Note that a counterbalance mechanism can be applied also to a measuringprobe 400 shown in the third embodiment. For example, the presentinvention may be configured as in the seventh embodiment shown in FIG.10. The seventh embodiment is different from the third embodiment in theaddition of a counterbalance mechanism different from that in the fourthembodiment. Thus, for components excluding those different from thethird embodiment, basically the first two digits of their referencenumerals are simply changed from the third embodiment and thedescription thereof will be omitted.

In the seventh embodiment, a probe main body 802 includes: a balanceweight 831CD corresponding to the mass of a stylus 806; andcounterbalance mechanisms 831 as shown in FIG. 10. Unlike the fifthembodiment, the three counterbalance mechanisms 831 are separated fromthe stylus 806, and fixed to a main body housing (axial element housingmember) 808. The three counterbalance mechanisms 831 are supported bythe main body housing 808, and configured to keep the stylus 806 and thebalance weight 831CD in balance in the Z direction. Specifically, thecounterbalance mechanism 831 includes: a supporting member 831A; asupport shaft 831B; a coupling portion 831CA; a permanent magnet 831CB;and a coupling shaft 831D. The supporting members 831A are disposed atintervals of 120 degrees in the circumferential direction on a lower endof the main body housing 808. The support shaft 831B is fixed to thesupporting member 831A to support the coupling portion 831CA. Thecoupling shaft 831D is provided in a direction perpendicular to the Zdirection at an end of the coupling portion 831CA closer to the centralaxis O with respect to the support shaft 831B. On the other hand, aconnecting portion 812E is provided on a lower end of a moving member812. A tip of the coupling shaft 831D is coupled to the connectingportion 812E. The permanent magnet 831CB is disposed at an end of thecoupling portion 831CA opposite to the coupling shaft 831D with respectto the support shaft 831B.

As shown in FIG. 10, the balance weight 831CD has an annular shape(which may be divided corresponding to the number of the counterbalancemechanisms 831). A magnetic member (which may be a magnet) 831CCattractable to the permanent magnet 831CB is provided on an uppersurface of the balance weight 831CD. Note that an inner diameter of thebalance weight 831CD is set to be greater than an outer diameter of aflange member 842 and a flange part 844. Thus, the attachment anddetachment of the balance weight 831CD are possible even after thecoupling of the stylus 806.

Thus, when the stylus 806 is replaced for the single probe main body802, the balance weight 831CD corresponding to the mass of the changedstylus 806 can be freely attached to the counterbalance mechanism 831.This allows the main body housing 808 to directly receive an increase ordecrease in the mass of the stylus 806. More specifically, fluctuationsin the initial position of the moving member 812 in the Z direction dueto different styluses 806 can be prevented by this configuration. Inother words, in the present embodiment, a range of motion for the movingmember 812 can be reduced when compared with the third embodiment, thusallowing further miniaturization of the probe main body 802. At the sametime, the detection range can be reduced, thus allowing the detection ofan amount of displacement of the moving member 812 with a higherresolution.

In the third embodiment, the distance between the lower end 408AB of theopening 408A and the upper end 442C of the flange member 442 isdetermined to regulate displacement of the moving member 412 so that anamount of deformation in the pair of first diaphragm structures 414 and415 falls within the range of elastic deformation. In other words, itcan be said that the probe main body 402 includes the main body housing408 and the flange member 442 together serving as the first limitingmember for limiting an amount of deformation in the pair of firstdiaphragm structures 414 and 415 within the range of elasticdeformation. By contrast to this, the present invention may beconfigured as in the eighth embodiment shown in FIG. 11A, for example.The eighth embodiment is different from the third embodiment mainly inrelationship between a main body housing and a moving member andrelationship between a rotating member and the moving member. Thus, forcomponents excluding those associated with the relationship between themain body housing and the moving member and the relationship between therotating member and the moving member, basically the first two digits oftheir reference numerals are simply changed from the fifteenthembodiment and the description thereof will be omitted.

In the eighth embodiment, a ring portion 862C is provided at a lower endof a moving member (rotary element housing member) 862 so as to face anupper end of a coupling portion 886A of a rotating member RP as shown inFIG. 11A. In other words, it can be said that the ring portion 862C is asecond wall member disposed integrally with the moving member 862. Atleast part of a gap between (a lower end of) the ring portion 862C and(an upper end of) the coupling portion 886A is filled with a secondviscous material SV, such as a grease oil. Consequently, at least thesecond viscous material SV can damp the displacement of the rotatingmember RP with respect to the ring portion 862C, reduce vibration in theXY direction caused by the movement of a measuring probe 850, forexample, and prevent an increase in noise associated with an increase inthe sensitivity of the measuring probe 850.

Also, an inner wall portion 858B is provided in a main body housing(axial element housing member) 858 so as to face an outer side surfaceof the moving member 862 as shown in FIG. 11A. In other words, it can besaid that the inner wall portion 858B is a first wall member disposed soas to face the moving member 862 and to be integral with the main bodyhousing 858. At least part of a gap between (an inner side surface of)the inner wall portion 858B and (an outer side surface of) the movingmember 862 is filled with a first viscous material FV, such as a greaseoil. Consequently, at least the first viscous material FV can damp thedisplacement of the moving member 862 with respect to the inner wallportion 858B, reduce vibration in the Z direction caused by the movementof the measuring probe 850, for example, and prevent an increase innoise associated with an increase in the sensitivity of the measuringprobe 850.

Furthermore, in the present embodiment, damping structures in the Zdirection and the XY direction are separately provided also. Thus, thefirst viscous material FV and the second viscous material SV can beindividually changed. The damping characteristics in the Z direction andthe XY direction can be therefore individually optimized, thus allowinga further increase in the sensitivity of the measuring probe 850.

As shown in FIG. 11A, the main body housing 858 is provided with adepressed portion 858C that houses a flange member 892 and restrictsexcessive displacement of the flange member 892. Also, the inner wallportion 858B is provided in the vicinity of a joining portion 862D ofthe moving member 862 in the Z direction. Thus, a distance between anupper end 858BA of the inner wall portion 858B and a lower end 862DA ofthe joining portion 862D of the moving member 862 and a distance betweenan upper end 858CA of the depressed portion 858C and an upper end 892Bof the flange member 892 are determined to regulate displacement of themoving member 862 so that an amount of deformation in a pair of firstdiaphragm structures 864 and 865 falls within the range of elasticdeformation. In other words, it can be said that a probe main body 852includes the main body housing 858, the moving member 862, and theflange member 892 together serving as a first limiting member forlimiting an amount of deformation in the pair of first diaphragmstructures 864 and 865 within the range of elastic deformation.

Moreover, a distance between a side surface 858CB of the depressedportion 858C and a side surface 892A of the flange member 892 isdetermined to regulate displacement of the rotating member RP so that anamount of deformation in a second diaphragm structure 890 falls withinthe range of elastic deformation as shown in FIG. 18A. In other words,it can be said that the probe main body 852 includes the main bodyhousing 858 and the flange member 892 together serving as a secondlimiting member for limiting an amount of deformation in the seconddiaphragm structure 890 within the range of elastic deformation.

FIG. 11B shows the ninth embodiment, which is a variation of the presentembodiment, regarding the first viscous material FV and the secondviscous material SV. Here, the supporting of the axial motion mechanismby the rotary motion mechanism leads to the direct supporting of thestylus by the moving member as with the first embodiment, etc. The ninthembodiment is different from the first embodiment, etc., mainly inconfigurations for retaining the first viscous material FV and thesecond viscous material SV. Thus, for components excluding thoseassociated with the first viscous material FV and the second viscousmaterial SV, basically the first two digits of their reference numeralsare simply changed from the first embodiment and the description thereofwill be omitted. Note that a displacement detector (not shown) issupported as in the first embodiment, etc. As shown in FIG. 11B, astylus 906 is directly fixed to a moving member 912 with a flange part944 without employing a kinematic joint.

In the ninth embodiment, an inner side surface of a cylindrical portion936C of a rotating member (axial element housing member) 936 is disposedso as to face an outer side surface of the moving member 912 as shown inFIG. 11B. In other words, it can be said that the rotating member 936 isa first wall member disposed so as to face the moving member 912. Then agap between (the inner side surface of) the cylindrical portion 936C and(the outer side surface of) the moving member 912 is filled with thefirst viscous material FV, such as a grease oil. Consequently, at leastthe first viscous material FV can damp the displacement of the movingmember 912 with respect to the rotating member 936, reduce vibration inthe Z direction caused by the movement of a measuring probe 900, forexample, and prevent an increase in noise associated with an increase inthe sensitivity of the measuring probe 900.

Also, a viscous material receiver 931 is provided so as to cover asecond diaphragm structure 940 from the both sides thereof as shown inFIG. 11B. The viscous material receiver 931 is fixed to a main bodyhousing (rotary element housing member) 908 with its members, eachintegrally formed by an opposed portion 931A and an expanded portion931B, facing each other. The opposed portion 931A is a portion facingthe second diaphragm structure 940. The expanded portion 931B is aportion covering a joining portion 936D of the moving member 912 in acontactless manner and provided with an opening 931C through which thecylindrical portion 936C can pass. In other words, it can be said thatthe viscous material receiver 931 is a second wall member disposed to beintegral with the main body housing 908. A gap between (an inner sidesurface of) the viscous material receiver 931 and the second diaphragmstructure 940 is filled with the second viscous material SV, such as agrease oil. Consequently, at least the second viscous material SV candamp the displacement of the second diaphragm structure 940 with respectto the viscous material receiver 931, reduce vibration in the XYdirection caused by the movement of the measuring probe 900, forexample, and prevent an increase in noise associated with an increase inthe sensitivity of the measuring probe 900.

Furthermore, in the present embodiment, damping structures in the Zdirection and the XY direction are separately provided also. Thus, thefirst viscous material FV and the second viscous material SV can beindividually changed. The damping characteristics in the Z direction andthe XY direction can be therefore individually optimized, thus allowinga further increase in the sensitivity of the measuring probe 900.

Although the orientation detector is incorporated in the probe main bodyin the first to ninth embodiments, the present invention is not limitedthereto. For example, the present invention may be configured as in thetenth embodiment shown in FIG. 10. In the tenth embodiment, the probemain body in the first and second embodiments is separable between abeam splitter and a reference member in the axial direction O. In otherwords, the tenth embodiment is different from the first and secondembodiments mainly in the position of an orientation detector. Thus, forcomponents mainly excluding those associated with the position of theorientation detector, basically the first two digits of their referencenumerals are simply changed from the first and second embodiments andthe description thereof will be omitted.

In the tenth embodiment, there is provided, as shown in FIG. 12, apreceding module 951, which detachably couples and supports a main bodyhousing 958 that supports both of a moving member 962 and a rotatingmember 986 with a V-groove (which may be a pair of rollers) 951BB and aball 957B (engagement part) capable of positioning the main body housing958. An orientation detector 972 is incorporated in the preceding module951.

Specifically, the preceding module 951 includes: a preceding housing(preceding housing member) 951A; and the orientation detector 972 asshown in FIG. 12. The preceding housing 951A supports the orientationdetector 972 radially inside thereof. The preceding housing 951A isprovided with a lower cover 951B at a lower end thereof. The lower cover951B has a flange shape with an opening 951BA at its center. Along aperiphery on a lower end of the lower cover 951B, three V-grooves 951BBare provided at intervals of 120 degrees in the circumferentialdirection as shown in FIG. 12. Three permanent magnets 951BC areprovided so as to be out of phase with the V-grooves 951BB by 60 degreesin the circumferential direction. In other words, the preceding housing951A detachably couples and supports the main body housing 958 with theV-grooves 951BB and the balls 957B capable of positioning the main bodyhousing 958. The preceding housing 951A houses the orientation detector972.

As shown in FIG. 12, a probe main body 952 includes: an upper cover 957;the main body housing 958; and a rotary motion mechanism 984. As shownin FIG. 12, the upper cover 957 has a flange shape with an opening 957Aat its center. The upper cover 957 is a member corresponding to thelower cover 951B (the opening 957A thus ensures the provision of anoptical path for incident light to a reference member (not shown)disposed on an upper end of a balancing member 988, for example, andreflected light from the reference member). Moreover, three balls 957Bare disposed at intervals of 120 degrees in the circumferentialdirection of the upper cover 957 so as to be in contact with therespective V-grooves 951BB. A magnetic member (which may be a permanentmagnet) 957C is disposed so as to correspond to the permanent magnet951BC. In other words, the lower cover 951B and the upper cover 957together constitute a kinematic joint, which is a detachable couplingmechanism. Such a kinematic joint allows for a high degree ofpositioning reproducibility even when attachment and detachment betweenthe lower cover 951B and the probe main body 952 are repeatedlyperformed.

As described above, in the present embodiment, the orientation detector972 can be eliminated from the probe main body 952 and the orientationdetector 972 is incorporated in the preceding module 951. Thus, theprobe main body 952 can be easily changed and the preceding module 951can also be easily changed. More specifically, change in performance orreplacement of the set of the axial motion mechanism 960, the rotarymotion mechanism 984, and the displacement detector 976 and that of theorientation detector 972 can be independently performed and the costthereof can be reduced. Moreover, since the orientation detector 972 canbe separated from the probe main body 952, the size and cost of theprobe main body 952 can be reduced.

Although the moving member 962 directly supports the stylus 906 in thepresent embodiment, the preceding module may be provided in the casethat the rotating member RP directly supports the stylus as in theeighth embodiment.

Although the center of gravity of the members supported by the seconddiaphragm structure, including the stylus, basically, coincides with therotation center RC in the above-described embodiments, the presentinvention is not limited thereto. For example, the center of gravity ofthe members supported by the second diaphragm structure, including thestylus, may be set on purpose on a side closer to the stylus withrespect to the rotation center RC. In this case, the mass and volume ofthe members supported by the second diaphragm structure on a sideopposite to the stylus with respect to the rotation center RC can beminimized. This allows a measuring probe to have an increased naturalfrequency and a measuring probe having sensitivity to a frequency higherthan that in the measuring probes of the first to tenth embodiments(e.g., capable of a fast response) can be thus achieved.

Although the measuring probe is used as a scanning probe in the aboveembodiments, the present invention is not limited thereto. For example,the measuring probe may be used as a touch probe.

Although the displacement detector is directly supported by the axialelement housing member that supports the moving member in the aboveembodiment, the present invention is not limited thereto. For example,the displacement detector may be supported by the rotary element housingmember that supports the rotating member RP or by the preceding module.

The present invention can be widely applied to measuring probes used formeasuring a three-dimensional shape of an object to be measured.

It should be apparent to those skilled in the art that theabove-described embodiments are merely illustrative which represent theapplication of the principles of the present invention. Numerous andvaried other arrangements can be readily devised by those skilled in theart without departing from the spirit and the scope of the invention.

1. A measuring probe, comprising: a stylus having a contact part; anaxial motion mechanism having a moving member that allows the contactpart to move in an axial direction; and a rotary motion mechanism havinga rotating member that allows the contact part to move along a planeperpendicular to the axial direction, wherein the axial motion mechanismincludes a plurality of first diaphragm structures that allow the movingmember to be displaced, and the rotary motion mechanism includes asecond diaphragm structure that allows the rotating member to bedisplaced, the second diaphragm structure is disposed between theplurality of first diaphragm structures in the axial direction, thefirst diaphragm structures are disposed at a symmetric distance withrespect to the second diaphragm structure, and the axial motionmechanism supports the rotary motion mechanism, or the rotary motionmechanism supports the axial motion mechanism.
 2. The measuring probeaccording to claim 1, wherein when a particular type of the stylus issupported by the rotating member, a center of gravity of memberssupported by the second diaphragm structure coincides with a rotationcenter of the rotary motion mechanism.
 3. The measuring probe accordingto claim 1, wherein the rotating member includes a balancing member on aside opposite to the stylus with respect to a rotation center of therotary motion mechanism, and a distance between the rotation center andthe balancing member is adjustable.
 4. The measuring probe according toclaim 1, further comprising a balance weight corresponding to a mass ofthe stylus, and a counterbalance mechanism supported by an axial elementhousing member for supporting the axial motion mechanism, thecounterbalance mechanism keeping the stylus and the balance weight inbalance.
 5. The measuring probe according to claim 1, further comprisingan axial element housing member that supports the axial motionmechanism, wherein the axial element housing member is provided with adisplacement detector for detecting displacement of the moving member.6. The measuring probe according to claim 5, wherein the displacementdetector outputs a relative position detection signal that allowsdetection of a relative position of the moving member.
 7. The measuringprobe according to claim 5, wherein the displacement detector outputs anabsolute position detection signal that allows detection of an absoluteposition of the moving member.
 8. The measuring probe according to claim5, wherein the axial element housing member is provided with aninterference optical system including an interference light source, areference mirror for reflecting light from the interference lightsource, and a target mirror disposed in the moving member for reflectinglight from the interference light source, the interference opticalsystem capable of causing interference of reflected light from thereference mirror and the target mirror to generate a plurality ofinterference fringes, and the displacement detector can detect a phaseshift of the plurality of interference fringes generated in theinterference optical system.
 9. The measuring probe according to claim1, further comprising a preceding housing member that detachably couplesand supports a housing member that supports both of the moving memberand the rotating member with an engagement part capable of positioningthe housing member, wherein a reference member is provided on an end,opposite to the stylus, of any of the rotating member and a membersupported by the rotating member, and an orientation detector fordetecting displacement of the reference member corresponding to a rotarymovement of the stylus is housed in the preceding housing member. 10.The measuring probe according to claim 1, further comprising a referencemember provided on an end, opposite to the stylus, of any of therotating member and a member supported by the rotating member, and anorientation detector for detecting displacement of the reference membercorresponding to a rotary movement of the stylus is housed in a housingmember that supports both of the moving member and the rotating member.11. The measuring probe according to claim 9, wherein the referencemember is a reflecting mirror for reflecting light, the measuring probeincludes a light source for causing light to be incident on thereflecting mirror along an optical axis, and the orientation detectordetects displacement of reflected light, reflected from the reflectingmirror, from the optical axis.
 12. The measuring probe according toclaim 11, wherein the optical axis is provided to pass through therotation center of the rotary motion mechanism.
 13. The measuring probeaccording to claim 1, further comprising a limiting member for limitingan amount of deformation in the plurality of first diaphragm structureswithin a range of elastic deformation.
 14. The measuring probe accordingto claim 1, further comprising a limiting member for limiting an amountof deformation in the second diaphragm structure within a range ofelastic deformation.
 15. The measuring probe according to claim 1,wherein at least part of a gap between a wall member, which is disposedto face the moving member and to be integral with the axial elementhousing member for supporting the axial motion mechanism, and the movingmember, is filled with a viscous material.
 16. The measuring probeaccording to claim 1, wherein at least part of a gap between a wallmember, which is disposed to be integral with a rotary element housingmember for supporting the rotary motion mechanism, and any of the seconddiaphragm structure and the rotating member, is filled with a viscousmaterial.